Collapsible sawhorse

ABSTRACT

A support structure has a first leg, a second leg, eg, a second leg, a third leg and a fourth leg. Each of these legs has a top portion, a center portion, and a bottom portion. The first leg includes a first hinge and a first stop. The first hinge connects the first leg center portion and the second leg center portion. The first hinge allows rotation of the second leg with respect to the first leg. The first leg center portion includes the first stop for limiting the rotation of the second leg with respect to the first leg.

RELATED APPLICATIONS

This patent application claims the benefit of Provisional PatentApplication 60/880,128, filed Jan. 12, 2007 and entitled “CollapsibleSawhorse,” incorporated herein by reference.

FIELD

This patent application generally relates to a structure for supportinga work piece. More particularly it relates to a sawhorse that is easilyadjustable in height and that collapses for storage and transportation.

BACKGROUND

A traditional sawhorse is used for supporting a work piece either byitself or in conjunction with another sawhorse. The traditional sawhorseusually takes on an A-frame structure and is generally rigid with afixed height. The rigidness of the sawhorse means it takes upsubstantial space and is hard to transport and move compactly. The fixedheight of the sawhorse makes it less accommodating to people of varyingheight. The fixed height also does not allow for ease of use in jobswhere being able to vary the work height maybe of benefit. Some sawhorsedesigns have had legs that could be disassembled or folded. Others havehad extendable legs. Although past designs offer some degree ofimprovement over the traditional rigid sawhorse, there exists a need fora stable sawhorse that is fully collapsible, has adjustable height, iseasy to set up and take down, and is very sturdy when in use. Thus,improved saw horse designs are needed, and embodiments of such designsare provided in the present patent application.

SUMMARY

One aspect of the present patent application is a support structure,comprising a first leg, a second leg, a third leg and a fourth leg. Eachof these legs has a top portion, a center portion, and a bottom portion.The first leg includes a first hinge and a first stop. The first hingeconnects the first leg center portion and the second leg center portion.The first hinge allows rotation of the second leg with respect to thefirst leg. The first leg center portion includes the first stop forlimiting the rotation of the second leg with respect to the first leg.

Another aspect of the present patent application is a support structure,comprising a first leg, a second leg, a third leg and a fourth leg. Eachof these legs has a top portion, a center portion, and a bottom portion.The first leg center portion overlaps the second leg center portion. Thethird leg center portion overlaps the fourth leg center portion. Thefirst leg has a first width in the first leg center portion. The firstleg has a second width outside the first leg center portion. The firstwidth is greater than the second width.

Another aspect of the present patent application is a support structure,comprising a first leg, a second leg, a third leg and a fourth leg. Eachof these legs has a top portion, a center portion, and a bottom portion.The support structure also includes a first hinge and a second hinge.The first hinge connects the first leg center portion and the second legcenter portion while the second hinge connects the third leg centerportion and the fourth leg center portion. The first hinge allowsrotation of the second leg with respect to the first leg while thesecond hinge allows rotation of the forth leg with respect to the thirdleg. The first leg center portion and the second leg center portion aremortised and the third leg center portion and the fourth leg centerportion are mortised.

Another aspect of the present patent application is a support structure,comprising a first leg, a second leg, a third leg and a fourth leg. Eachof these legs has a top portion, a center portion, and a bottom portion.The support structure also includes a bar and a hinge. The hinge extendsbetween the first leg and the second leg. The hinge extends through thebar. The hinge includes a device having a variable length.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing will be apparent from the following detailed descriptionas illustrated in the accompanying drawings, for clarity not drawn toscale, in which:

FIG. 1 a is a front three dimensional view of a structure according toone embodiment of the present patent application illustrating twoscissor sides and a horizontal top member for supporting a piece ofwork;

FIG. 1 b is a side three dimensional view of the structure in FIG. 1 a;

FIG. 2 a is a right side view of the structure in FIG. 1 a fullycollapsed;

FIG. 2 b is a front view of the structure in FIG. 1 a fully collapsed;

FIG. 2 c is a left side view of the structure in FIG. 1 a fullycollapsed;

FIG. 3 a is a cut away, three dimensional view of one embodiment of partof an elongate structure hinge assembly that includes a pin and a springused to connect components of the collapsible sawhorse;

FIG. 3 b is a side view of the hinge assembly of FIG. 3 a connectingcomponents of the collapsible sawhorse;

FIG. 3 c is a side view of the saw horse in open position looking towardthe end with the elongate structure hinge assembly of FIG. 3 a;

FIG. 3 c is a side view of the saw horse in closed position lookingtoward the end with the elongate structure hinge assembly of FIG. 3 a;

FIG. 4 a is another front view of the structure of FIG. 1 a in the fullycollapsed state;

FIG. 4 b is a front view of the structure in FIG. 4 a with the scissorsides open and the horizontal top member rotated out of its lockedposition;

FIG. 4 c is a front three dimensional view of the structure in FIG. 4 bwith the scissor sides extended and the horizontal top member lockedinto place;

FIG. 4 d is a front view of the structure in FIG. 4 c showing details ofthe locking of the horizontal top member to one of the hinges of the sawhorse;

FIG. 5 a is a front three dimensional view of the structure forsupporting a piece of work set to a first height;

FIG. 5 b is a front three dimensional view of the structure in FIG. 5 aset to a second height;

FIG. 6 is a three dimensional view of the structure in FIG. 5 a showingvarious ways of using the structure to support a piece of work;

FIG. 7 a is an exploded three dimensional view of two legs of onescissor side of the structure of FIG. 1 showing details of their hingedconnection; and

FIG. 7 b is a three dimensional view of the legs of FIG. 7 a whenconnected to each other at the hinge connection.

DETAILED DESCRIPTION

One embodiment of sawhorse 10 includes first scissor side 12, secondscissor side 14 and horizontal top member 16, as shown in FIGS. 1 a and1 b. First scissor side 12 includes a pair of crossed leg members 18 and20. Crossed leg members 18 and 20 include top portions 18 t, 20 t,center portions 18 c, 20 c, and bottom portions 18 b, 20 b. Crossed legmembers 18 and 20 are joined together by hinge 22 in center portions 18c, 20 c, which is near the midpoint of each leg member 18, 20.

Similarly, second scissor side 14 includes a pair of crossed leg members24 and 26 with the crossed leg members joined together in region 27 byhinge 28, which is near the midpoint of each leg member 24, 26.

Top ends 18 t and 20 t of first scissor side 12 are connected to topends 26 t and 24 t of second scissor side 14 at first hinge 30 andsecond hinge 32, respectively. Hinges 30 and 32 allow bottom ends 18 b,20 b, 24 b and 26 b of cross legged members 18, 20, 24 and 26 to bespread apart to generate a stable support structure.

Spreading apart of bottom ends 18 b, 20 b, 24 b and 26 b is limited toan angle at which top ends 18 t, 20 t, 24 t, 26 t press againsthorizontal top member 16. Cable 33 connects between hinge 22 and hinge28 to also limit the amount of spreading between each scissor side 12,14.

In this embodiment, hinge 30 includes elongated structure 31, as shownin FIGS. 3 a, 3 c, and 3 d, that passes through horizontal top member 16at end 16 a. Horizontal top member 16 can rotate around elongatedstructure 31, as shown in FIGS. 4 b, 4 c. End 16 b of horizontal topmember 16 is fitted with notch 34 that rests on hinge 32. Severalnotches 34 can be provided, allowing sawhorse 10 to have a variableheight.

Traction bumps 36 may be provided on the angled portions 37 of bottomends 18 b, 20 b, 24 b and 26 b of crossed legs 18, 20, 24, 26, as shownin FIGS. 1 a, 2 b. A stable structure for supporting a piece of work iscreated when crossed legs 18, 20 and crossed legs 24 and 26 are spreadapart parallel to horizontal top member 16 and when bottom ends 18 b, 20b of scissor sides 12 and bottom ends 24 b and 26 b of scissor sides 14are also spread apart perpendicular to horizontal top member 16.

Crossed leg members 18, 20, 24 and 26 may be fabricated from a laminatedwood material, plastic, steel or any other rigid material such asfiberglass, aluminum, titanium, and carbon composite materials. They maybe fabricated with elongated holes 38 or similar cut away structures tohelp reduce the weight of sawhorse 10, still providing it with strengthand rigidity. Elongated holes 38 or similar grooved structures also actto aid the user in grasping or carrying sawhorse 10.

Hinges 22 and 28 may be bolts. Hinges 22 and 28 may be made of the samematerial as the crossed leg members. Hinges 22 and 28 can also be madeof a different one of these materials that provides lower friction forpivoting. Hinges 22 and 28 can also be molded integrated in a singlepiece with crossed leg members 18, 20, and 24, 26, and one or morematerials can be used for the leg and hinge portions of this moldedintegrated component. Hinges 22 and 28 may also include a nylon washerwhere center portion 18 c of leg member 18 makes contact with centerportion 20 c of leg member 20 and where center portion 24 c of legmember 24 makes contact with center portion 26 c of leg member 26 toreduce friction.

Horizontal member 16 may also be fabricated from wood, plastic, steel orany other rigid material. Horizontal member 16 may also be fitted with asurface that is replaceable if it is cut or worn.

In one embodiment horizontal member 16 is a 2×4 piece of lumber thatrests on both hinges and is not connected to sawhorse 10 with hinge 30.To be used in this embodiment hinge 30 is not needed and a hinge likehinge 32 may be used instead. In this embodiment the sawhorse may opento a height defined by a stop integrated in hinges 22 and 28, as shownin FIG. 7 and described herein below. The 2×4 serves to limit thespreading of scissor sides 12 and 14 perpendicular to the 2×4. The 2×4can be removed and stored separately before collapsing the sawhorse.

In one embodiment, sawhorse 10 includes male spacer 27 and female spacer29 located on the inner sides of hinges 28 and 22, as shown in FIGS. 1a, 1 b and 2 a. Female spacer 29 is located and designed to receive malespacer 27. In one embodiment, in the collapsed state of sawhorse 10,male spacer 27 fits within female spacer 29. Spacers 27, 29 stop topmember 16 from swinging back and forth past hinges 22, 28 during theprocess of collapsing sawhorse 10. Also when engaged, spacers 27, 29limit the amount of twist that can occur in sawhorse 10 in the collapsedstate.

When crossed leg members 18, 20, 24, 26 are rotated to provide zeroangle between legs 18 and 20 and between legs 24 and 26 and when bottomends 18 b, 20 b of scissor sides 12 and bottom ends 24 b and 26 b ofscissor sides 14 are pushed together, sawhorse 10 will be in a closed orfully collapsed state, as shown in FIGS. 2 a-2 c. Here each pair ofcrossed legged members 18, 20 and 24, 26 are collapsed parallel to eachother. Hinge 30 still passes through first end 16 a of top member 16.Horizontal top member 16 can be rotated clockwise around hinge 30 toalso lie parallel to crossed leg members 18, 20 and 24, 26 between twocollapsed scissor legs 12, 14. Spacers 27, 29 prevent horizontal topmember 16 from swinging through, and hinges 30, 32 provide for enoughwidth to allow horizontal top member 16 to fit between collapsed scissorsides 12 and 14. In this collapsed state, hinge 30 and hinge 32 areadjacent each other.

Leg members 18, 20, 24 and 26 have tapered angles 40 at top ends 18 t,20 t, 24 t and 26 t, as shown in FIGS. 2 a, 2 c, to accommodate thedesired amount of spreading that will occur when bottom ends 18 b, 20 bof scissor sides 12 and bottom ends 24 b and 26 b of scissor sides 14are spread apart. The taper of angles 40 is typically around 20 degrees.When bottom ends 18 b, 20 b, 24 b, and 26 b of scissor sides 12, 14 arespread apart, tapered top ends 18 t, 20 t, 24 t and 26 t press againsthorizontal top member 16 preventing further spreading of bottom ends 18b, 20 b, 24 b, and 26 b.

Multiple notches 34 a-c are provided in the bottom of horizontal member16 to allow for multiple height adjustments, as shown in FIGS. 1 a, 2 b,and 4 b. Retaining strap 42 is used to hold all pieces of sawhorse 10tightly together when in the collapsed state, as shown in FIGS. 2 a-2 c.Horizontal member 16 may also have a hanging hole 44 to allow forhanging of sawhorse 10 on a wall when in the collapsed state, as shownin FIG. 2 b.

Sawhorse 10 folds to a fraction of its open or in-use size when it is inits closed or collapsed state. For example, when open the rectilinearvolume may be 23.5 inches wide by 30.5 inches long by 29.5 inches high,or a volume of 21,144 cubic inches. In the collapsed state, the samesawhorse 10 has dimensions of 4 inches wide by 5.5 inches long by 46inches high, or 1,012 cubic inches. This is a 21-to-1 volume reduction.

Hinge 30 flexibly connects top ends 20 t and 26 t of leg members 20 and26 together while allowing bottom ends 20 b, 26 b to be spread apart, asshown in FIGS. 3 c, 3 d. Hinge 30 extends through end 16 a of horizontaltop member 16, supporting end 16 a of horizontal top member 16 andallowing horizontal top member 16 to rotate around axis 45 of hinge 30.Hinge 30 has a variable length L sufficient to provide spacing betweentop ends 20 t and 26 t of leg members 20 and 26 for horizontal topmember 16 to fit between scissor sides 12 and 14 when sawhorse 10 iscollapsed.

Elongated structure 31 of hinge 30 includes pin 46 a, large coiledspring 46 b, small springs 46 c, and washer 46 d, as shown in FIG. 3 a.Large coiled spring 46 b makes length of elongated support structure 31adjustable to accommodate variations in the angular spacing betweenscissor sides 12 and 14 when saw horse 10 is set for different heightsor is collapsed for storage.

Both ends of coiled spring 46 b have looped ends 48 that extend beyondpin 46 a all the way through holes 47 in top ends 20 t and 26 t of legmembers 20 and 26 respectively and through the hole of washer 46 d.Winged locking pins or S hooks 50 extend though looped ends 48 of coiledspring 46 b and hold coiled spring 46 b in place through top ends 20 tand 26 t of leg members 20 and 26, as shown in FIGS. 3 a, 3 b.

Top ends 20 t and 26 t of leg members 20 and 26 can have slots 54 wherelooped ends 48 of coiled spring 46 b reside, as shown in FIG. 3 b. Slots54 allow for hinge 30 to adjust for optimal positioning when crossedlegs 18, 20, 24, 26 are in either the open or collapsed state. Slot 54allows coiled spring 46 b to move up and down, providing give sosawhorse 10 can be set on a surface having up to ¾ inch of unevenness.Slot 54 also provides so extra space facilitating opening and closing ofleg members 20, 26.

Pin 46 a lies within coiled spring 46 b and provides support forhorizontal top member 16 on top ends of legs 20 t and 26 t when sawhorse 10 is in use in its open position, as shown in FIG. 3 c. AS sawhorse 10 is closed, pin 46 a pulls out of holes 47 in top ends 20 t, 26t of leg members 20, 26 allowing legs 20, 26 to rotate, as shown in FIG.3 d. Coiled spring 46 b expands and continues to extend through holes 47retaining pin 46 a in position for later reopening saw horse 10. Pin 46a is also held in position by small springs 46 c that fit inside coiledspring 46 b and keep pin 46 a centered within top member 16. Smallsprings 46 c are in compression mode between pin 46 a and washer 46 d.

Flex provided by coiled spring 46 b allows for cross legs 20, 26 toadjust for any uneven ground. Coiled spring 46 b is always under tensionso it is always pulling top ends 20 t, 26 t of legs members 20, 26together and toward top member 16. Spring tension in coiled spring 46 badds to pressure provided by top ends 20 t, 26 t pinching horizontal topmember 16 when bottom ends 18 b, 20 b, 24 b, 26 b of crossed legs 18,20, 24, 26 are spread apart. The stiffness of spring 46 b of hinge 30sets the amount of this contributor to pinching.

Sawhorse 10 is set up from the collapsed state as shown in FIGS. 4 a-c.First, retaining strap 42 is opened, as shown in FIG. 4 a. Top ends 18 tand 20 t of scissor legs 12 and top ends 24 t and 26 t of scissor legs14 are then pushed apart parallel to horizontal top member 16 to expandsaw horse 10, as shown in FIG. 4 b. During this process, horizontal topmember 16 is rotated counterclockwise around hinge 30, as also shown inFIGS. 4 b, 4 c until one of notches 34 a-34 c engages with hinge 32, asshown in more detail in FIG. 4 d. Bottoms of scissor legs 12 and 14 arethen spread apart perpendicular to horizontal top member 16 untilstopped by pressure of top ends 18 t, 20 t, 24 t, 26 t againsthorizontal top member 16. Retaining cable 33 may also restrain spreadingapart of scissor legs. Height of sawhorse 10 is adjusted by adjustingwhich notch 34 a-34 c engages with hinge 32. Sawhorse 10 is now fullyassembled and ready to be used to support a work piece. To collapsesawhorse 10, these steps are carried out in reverse.

Sawhorse 10 can be set to different working heights, as shown in FIGS. 5a, 5 b. To adjust the height of sawhorse 10, the user first assemblesthe sawhorse as described in the preceding paragraph to height H1. Thento raise sawhorse 10 to height H2, the user disengages notch 34 a ofhorizontal top member 16 from hinge 32 by lifting horizontal top member16 and pivoting it slightly upward around hinge 30. Top ends 18 t and 20t of cross legs 18 and 20 are brought a small amount closer togetherparallel to horizontal top member 16, as are top ends 24 t and 26 t ofcross legs 24 and 26. This action increases the height of the “X”structure. Horizontal top member 16 is then pivoted back in place toengage one of the alternative notches 34 b or 34 c with hinge 32. Theheight of sawhorse 10 may now be lowered by lifting horizontal topmember 16 off of notch 34 b or 34 c, spreading the cross leg structureparallel to horizontal top member 16 to lower the height of the “X”structure and engaging, for example, notch 34 a with hinge 32.

A board, pipe or similar piece of work may be directly placed on top ofhorizontal top member 16, as shown in FIG. 6. Two sawhorses 10 may beused to support long work pieces. Recess 56 may be fabricated intohorizontal top member 16 to securely hold two-by-four 58 in a particularplace. Working material, such as board 60 may be stored below horizontaltop member within the “X” structure created by crossed leg members 18,20, 24 and 26.

Hinge 22 includes overlapping regions 70, 70′ of central parts 18 c, 20c of legs 18, 20, as shown in FIG. 7. Hole 72, 72′ extends through thecenter of regions 70, 70′ and hinge 22 extends through hole 72 toprovide a pivot around which leg 18 can rotate with respect to leg 20.Hinge 22 can be integral with region 70′ of leg 18 or it can be aseparate piece, such as a bolt, that extends through holes 72, 72′ inoverlapping regions 70, 70′.

Stops 74 a, 74 b are located on two sides of region 70 of leg 20 andidentical stops 74 a′, 74 b′ are located on corresponding sides ofregion 70′ of leg 18. Thus, legs 18, 20 can rotate around hinge 22 untilthese stops 74 a, 74 b, 74 a′, 74 b′ meet, preventing further rotation,as shown in FIG. 7 b. Mortising overlapping regions 70, 70′ of legs 18,20 facilitates forming stops 74 a, 74 b, 74 a′, 74 b′. Mortising can beprovided by sizing legs 18, 20 in overlapping region 23 to be half thethickness of legs 18, 20 in other regions.

In one embodiment a nylon bushing having an area about equal to that ofregion 70 is placed between regions 70, 70′ to reduce friction therebetween. Leg 18 is thus free to rotate with respect to leg 20 from anangle in which top and bottom parts of leg 18 are parallel to leg 20 andside portions of legs 18 and 20 are touching each other, as shown inFIGS. 3 a-3 c, to an angle determined by the location of stops 74 a, 74b on leg 20 and complementary stops 74 a′, 74 b′ on leg 18. A similararrangement provides hinge 28 on central parts 24 c, 26 c of legs 24,26.

Leg 20 has a significantly larger width Wc in region 70 of hinge 22 thanthe width Wb it has outside region 70, for example toward bottom end 20b of leg 20, as shown in FIG. 7 a. Typically, Wc is about two times Wb.While leg 20 is free to rotate through a substantial angle with respectto leg 18 overlap region 70,70′ does not much change in area as anglechanges.

In addition to construction materials, such as lumber and pipes, theworkpiece supported by sawhorse 10 can, for example, be a table top, anappliance, or a display counter.

While the disclosed methods and systems have been shown and described inconnection with illustrated embodiments, various changes may be madetherein without departing from the spirit and scope of the invention asdefined in the appended claims.

1. A support structure, comprising: a first leg, a second leg, a thirdleg and a fourth leg, wherein each said leg has a top portion, a centerportion, and a bottom portion; and a first hinge and a first stop, saidfirst hinge connecting said first leg center portion and said second legcenter portion, wherein said first hinge allows rotation of said secondleg with respect to said first leg, wherein said first leg centerportion includes said first stop for limiting said rotation of saidsecond leg with respect to said first leg.
 2. A support structure, asrecited in claim 1, further comprising a second hinge connecting saidthird leg center portion and said fourth leg center portion, said secondhinge allowing rotation of said fourth leg with respect to said thirdleg.
 3. A support structure, as recited in claim 2, wherein said thirdleg center portion includes a third stop for limiting said rotation ofsaid fourth leg with respect to said third leg.
 4. A support structure,as recited in claim 2, further comprising a third hinge located betweensaid top portion of said first leg and said top portion of said thirdleg.
 5. A support structure, as recited in claim 4, further comprising afourth hinge located between said top portion of said second leg andsaid top portion of said fourth leg.
 6. A support structure, as recitedin claim 5, further comprising a bar extending between said top portionsof said first and second legs, wherein pressure of said top portions ofsaid first leg and said second leg pressing against said bar limitsrotation of said first leg and said second leg around said third hinge.7. A support structure, as recited in claim 6, wherein said first leg,said second leg, said third leg, and said fourth leg provide a stablestructure when said first leg and said second leg have rotated to saidfirst stop and when said top portions of said first leg and said secondleg have rotated toward top portions of said third leg and said fourthleg to provide said pressure.
 8. A support structure, as recited inclaim 6, wherein said fourth hinge extends through said bar, whereinsaid fourth hinge includes a variable spacing device.
 9. A supportstructure, as recited in claim 8, wherein said variable spacing deviceincludes a spring and a pin hinge.
 10. A support structure, as recitedin claim 2, wherein said first hinge includes a structure that extendstoward said second hinge.
 11. A support structure, as recited in claim10, wherein said second hinge includes a structure that extends towardsaid first hinge.
 12. A support structure, as recited in claim 1,further comprising a second stop, wherein said second leg center portionincludes said second stop for limiting said rotation of said first legwith respect to said second leg.
 13. A support structure, as recited inclaim 12, wherein said first stop limits rotation of said second legwith respect to said first leg at about the same rotational angle thatsaid second stop limits rotation of said first leg with respect to saidsecond leg.
 14. A support structure, as recited in claim 1, wherein saidfirst leg has a first width in said first leg center portion and whereinsaid first leg has a second width outside said first leg center portion,wherein said first width is greater than said second width.
 15. Asupport structure, as recited in claim 14, wherein said second leg has athird width in said second leg center portion and wherein said secondleg has a fourth width outside said second leg center portion, whereinsaid first width is identical to said third width and wherein saidsecond width is identical to said fourth width.
 16. A support structure,as recited in claim 1, wherein said first leg, said second leg, saidthird leg, and said fourth leg are identical.
 17. A support structure,as recited in claim 1, further comprising a bushing, wherein saidbushing is located between said first leg center portion and said secondleg center portion for reducing friction there between when said secondleg rotates with respect to said first leg.
 18. A support structure, asrecited in claim 1, wherein said first leg center portion includes afirst mortis and wherein said second leg center portion includes asecond mortis, wherein said first mortis connects with said secondmortis, wherein said first mortis includes a first edge, wherein saidfirst edge provides said first stop.
 19. A support structure, comprisinga first leg, a second leg, a third leg and a fourth leg, wherein eachsaid leg has a top portion, a center portion, and a bottom portion,wherein said first leg center portion overlaps said second leg centerportion and wherein said third leg center portion overlaps said fourthleg center portion, wherein said first leg has a first width in saidfirst leg center portion, and wherein said first leg has a second widthoutside said first leg center portion, wherein said first width isgreater than said second width.
 20. A support structure, comprising: afirst leg, a second leg, a third leg and a fourth leg, wherein each saidleg has a top portion, a center portion, and a bottom portion; and afirst hinge and a second hinge, said first hinge connecting said firstleg center portion and said second leg center portion, said second hingeconnecting said third leg center portion and said fourth leg centerportion, wherein said first hinge allows rotation of said second legwith respect to said first leg, wherein said second hinge allowsrotation of said forth leg with respect to said third leg, wherein saidfirst leg center portion and said second leg center portion are mortisedand wherein said third leg center portion and said fourth leg centerportion are mortised.
 21. A support structure, comprising: a first leg,a second leg, a third leg and a fourth leg, wherein each said leg has atop portion, a center portion, and a bottom portion; a bar and a hinge,wherein said hinge extends between said first leg and said second leg,wherein said hinge extends through said bar, wherein said hinge includesa device having a variable length.
 22. A support structure, as recitedin claim 21, wherein said variable spacing device includes a spring anda pin, wherein said spring is longer than said pin.
 23. A supportstructure, as recited in claim 21, further comprising a slot in saidfirst leg and in said second leg, wherein said variable length deviceextends through said slot.